Electro-Mechanical Simulation of Switching Characteristics for Nanoelectromechanical Memory

The static switching properties and readout characteristics of proposed high-speed and nonvolatile nanoelectromechanical (NEM) memory devices are investigated By conducting a three-dimensional finite element mechanical simulation combined with an electrostatic analysis, we analyze the electromechanical switching operation of a mechanically bistable NEM floating gate by applying gate voltage. We show that switching voltage can be reduced to less than 10V by reducing the zero-bias displacement of the floating gate and optimizing the cavity structure to improve mechanical symmetry. We also analyze the electrical readout property of the NEM memory devices by combining the electromechanical simulation with a drift-diffusion analysis We demonstrate that the mechanically bistable states of the floating gate can be detected via the changes in drain current with an ON/OFF current ratio of about 3 x 10 (C) 2009 The Japan Society of Applied Physic

Gauge Group and Topology Change

The purpose of this study is to examine the effect of topology change in the initial universe. In this study, the concept of $G$-cobordism is introduced to argue about the topology change of the manifold on which a transformation group acts. This $G$-manifold has a fiber bundle structure if the group action is free and is related to the spacetime in Kaluza-Klein theory or Einstein-Yang-Mills system. Our results revealed that fundamental processes of compactification in $G$-manifolds. In these processes, the initial high symmetry and multidimensional universe changes to present universe by the mechanism which lowers the dimensions and symmetries.Comment: 8 page

Rolling Tachyon Solution in Vacuum String Field Theory

We construct a time-dependent solution in vacuum string field theory and investigate whether the solution can be regarded as a rolling tachyon solution. First, compactifying one space direction on a circle of radius R, we construct a space-dependent solution given as an infinite number of *-products of a string field with center-of-mass momentum dependence of the form e^{-b p^2/4}. Our time-dependent solution is obtained by an inverse Wick rotation of the compactified space direction. We focus on one particular component field of the solution, which takes the form of the partition function of a Coulomb system on a circle with temperature R^2. Analyzing this component field both analytically and numerically using Monte Carlo simulation, we find that the parameter b in the solution must be set equal to zero for the solution to approach a finite value in the large time limit x^0\to\infty. We also explore the possibility that the self-dual radius R=\sqrt{\alpha'} is a phase transition point of our Coulomb system.Comment: 39 pages, 17 figures, v3: references adde

On the origin of thermal string gas

We investigate decaying D-branes as the origin of the thermal string gas of string gas cosmology. We consider initial configurations of low-dimensional branes and argue that they can time evolve to thermal string gas. We find that there is a range in the weak string coupling and fast brane decay time regimes, where the initial configuration could drive the evolution of the dilaton to values, where exactly three spacelike directions grow large.Comment: 16 pages, 4 figures, v2: references adde

The Final Fate of the Rolling Tachyon

We propose an alternative interpretation of the boundary state for the rolling tachyon, which may depict the time evolution of unstable D-branes in string theory. Splitting the string variable in the temporal direction into the classical part, which we may call "time" and the quantum one, we observe the time dependent behaviour of the boundary. Using the fermion representation of the rolling tachyon boundary state, we show that the boundary state correctly describes the time-dependent decay process of the unstable D-brane into a S-brane at the classical level.Comment: 9 pages, revte

Micro-optics for ultra-intense lasers

金沢大学先端科学・社会共創推進機構Table-top, femtosecond lasers provide the highest light intensities capable of extreme excitation of matter. A key challenge, however, is the efficient coupling of light to matter, a goal addressed by target structuring and laser pulse-shaping. Nanostructured surfaces enhance coupling but require “high contrast” (e.g., for modern ultrahigh intensity lasers, the peak to picosecond pedestal intensity ratio >1012) pulses to preserve target integrity. Here, we demonstrate a foam target that can efficiently absorb a common, low contrast 105 (in picosecond) laser at an intensity of 5 × 1018 W/cm2, giving ∼20 times enhanced relativistic hot electron flux. In addition, such foam target induced “micro-optic” function is analogous to the miniature plasma-parabolic mirror. The simplicity of the target—basically a structure with voids having a diameter of the order of a light wavelength—and the efficacy of these micro-sized voids under low contrast illumination can boost the scope of high intensity lasers for basic science and for table-top sources of high energy particles and ignition of laser fusion targets

Presentations of patients of poisoning and predictors of poisoning-related fatality: Findings from a hospital-based prospective study

<p>Abstract</p> <p>Background</p> <p>Poisoning is a significant public health problem worldwide and is one of the most common reasons for visiting emergency departments (EDs), but factors that help to predict overall poisoning-related fatality have rarely been elucidated. Using 1512 subjects from a hospital-based study, we sought to describe the demographic and clinical characteristics of poisoning patients and to identify predictors for poisoning-related fatality.</p> <p>Methods</p> <p>Between January 2001 and December 2002 we prospectively recruited poisoning patients through the EDs of two medical centers in southwest Taiwan. Interviews were conducted with patients within 24 hours after admission to collect relevant information. We made comparisons between survival and fatality cases, and used logistic regressions to identify predictors of fatality.</p> <p>Results</p> <p>A total of 1512 poisoning cases were recorded at the EDs during the study period, corresponding to an average of 4.2 poisonings per 1000 ED visits. These cases involved 828 women and 684 men with a mean age of 38.8 years, although most patients were between 19 and 50 years old (66.8%), and 29.4% were 19 to 30 years. Drugs were the dominant poisoning agents involved (49.9%), followed by pesticides (14.5%). Of the 1512 patients, 63 fatalities (4.2%) occurred. Paraquat exposure was associated with an extremely high fatality rate (72.1%). The significant predictors for fatality included age over 61 years, insufficient respiration, shock status, abnormal heart rate, abnormal body temperature, suicidal intent and paraquat exposure.</p> <p>Conclusion</p> <p>In addition to well-recognized risk factors for fatality in clinical settings, such as old age and abnormal vital signs, we found that suicidal intent and ingestion of paraquat were significant predictors of poisoning-related fatality. Identification of these predictors may help risk stratification and the development of preventive interventions.</p

A critical recuperation of Watsuji’s Rinrigaku

Watsuji is recognised as one Japan’s foremost philosophers. His work on ethics, Rinrigaku, is cosmopolitan in engaging the Western philosophical tradition, and in presupposing an international audience. Yet Watsuji’s ethical thought is largely of niche interest outside Japan, and it is critiqued on the ground that it ratifies totalitarianism, demanding individuals’ unquestioning subordination to communal demands. We offer a reading of Rinrigaku that, in attempting to trace the text’s intention, disputes these arguments. We argue that Rinrigaku makes individual autonomy central to ethical action, despite the fact that its treatment of coercion may lead one to think otherwise; that it does not reduce ethical obligations to whatever demands any given society imposes on its members; that it draws a distinction between socio-ethical orders that are genuinely ethical and those that are not; and that, in insisting on the grounding of individuals in the Absolute, it makes adequate room for individuals’ resistance to unjustifiable socio-ethical demands